Atherosclerotic cardiovascular disease is common, and is caused by a narrowing of the arterial lining due to atherosclerotic plaques. When plaque builds up, this is referred to in the art as stenosis. One method commonly employed to relieve arterial stenosis resulting from plaque build-up is percutaneous transluminal coronary angioplasty, or balloon angioplasty. PTCA or balloon angioplasty, is a non-invasive, non-surgical means of treating coronary arteries.
This technique consists of inserting a non-inflated balloon catheter into the affected artery. Dilation of the diseased segment of artery is accomplished by inflating the balloon which pushes the atherosclerotic lesion outward, compressing the stenosis and enlarging the arterial diameter.
To help prevent arterial closure, repair dissection, or prevent restenosis, a physician can also implant an intravascular prosthesis, or a stent, for maintaining vascular patency inside an artery or other vessel at the lesion.
Stents are also used for a variety of other purposes including maintaining the patency of any physiological conduit including arteries, veins, vessels, the biliary tree, the urinary tract, the alimentary tract, the tracheobronchial tree, the genitourinary system, and the cerebral aqueduct.
In combination with a stent, it has further been found to be advantageous to employ pharmacologically active therapeutic agents, such as those in the form of a drug eluting coating, to reduce the amount of restenosis caused by intimal hyperplasia.
Stents may be may either be self-expanding or balloon expandable. For the latter type, the stent is often delivered on a balloon and the balloon is used to expand the stent.
Whether the balloon is used for POBA or for stent delivery, one consideration is withdrawal resistance of the balloon after use. Depending on the material used to manufacture the balloon and the stent, and possibly stent coating, there may be friction between the balloon and stent surfaces. Also, if a sufficient amount of time is not allowed for the balloon to fully deflate after use, there may be resistance upon attempts to withdraw the balloon from the treatment site.
One way to remedy this is to provide a lubricious coating between the outer balloon surface and the inner stent surface.
Other considerations in the manufacture of a balloon include reliable inflation to a predetermined diameter when the balloon is infused with inflation media, and the balloon must have the ability to collapse and fold to a minimal, radially compact cross-sectional shape after use to facilitate withdrawal.
It can be difficult to achieve all of these properties when constructing a balloon from a single polymer material.
There remains a need for innovative and improved balloon construction to achieve the desired balance of properties.